Mixer line out into K-5IIs external mic socket.

Revisiting the microphone input on a K5iis; my goal is to record my daughter playing a midi keyboard. I am trying to get better quality than a microphone recording the output of the small speakers we have on the midi.

I was hoping to run from the midi keyboard through a small mixer I have and then run the mixer output into the camera. The goal being that the camera will sync it for us.

That way I would save the hassle of recording the sound separate and then trying to sync sound and video. I have explored that already and its hard to do on Windows.

I guess it boils down to if the camera would be capable of recording in stereo from it's external mic socket if I trial and error the audio levels from the mixer.

the problem you will have is matching levels to prevent overload of the mic inputs on K5 & possible excessive noise. You don't really need a mixer, you just need to match the levels between the source, (in this case the line out or possibly headphone out) to the mic input level required by the camera. The output of the midi keyboard will be to "hot" for the mic input. This can be solved by using an attenuator cable. This is quite easy for me to say as being a tech I can just make up the cable & fit the appropriate resistors to match the levels. I think cables would be available for this function. Finding an attenuator cable with the right amount of attenuation and the right connectors at each end may be a challenge though. However I'm sure this would have been done before and would be suprised if there wasn't a commercially available solution.

Using a mixer will enable you to match the levels however it intoduces a number of possible noise sources, channel noise should not be an issue as this gets tuned down and reduces as you turn the signal down, but mixers have residual output stage noise which may be a problem when connected to a mic input. If you can find a "Passive mixer" ( no active gain stages ) this will do the job of reducing the levels without introducing any noise. ( a passive mixer doesn't require batteries or power supply to work - it just contains a number of variable resistors to mix signals together)